System, Method, and Apparatus for Determining an End-of-Train Position

ABSTRACT

A system, method, and apparatus for determining a location of a train as it travels on a track network is provided. The system includes an end-of-train device located on an end of the train, the end-of-train device comprising at least one signal receiving device configured to activate and receive transponder data from a plurality of passive transponders located throughout at least a portion of the track network. The system also includes at least one processor in communication with the at least one signal receiving device, the at least one processor programmed or configured to determine a location of the train based at least partially on at least a portion of the transponder data.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to determining the position of a trainand, in particular, a system, method, and apparatus for determining theposition of an end of a train by using passive transponders in a railnetwork.

Description of Related Art

Safety concerns in managing a track network require vital separationbetween trains that could potentially occupy the same physical space.Aside from potential collisions, another concern is the presence oftrains on a track segment where some action is occurring, such as themovement of a switch from one alignment to another.

Traditionally, detecting the presence of a train has been performed byusing track circuits or axle counters. Track circuits detect thepresence of a train and use that detection to provide vital interlockingfor switch position changes or signal indications for other trains in agiven track network. For example, if a train is present on a particulartrack circuit that is associated with a switch, it would be known thatthe switch alignment cannot be changed because it would occur underneatha moving train and cause a derailment. Further, track circuits are usedto detect the presence of a train in a given block (e.g., in a fixedblock signal system) to indicate to other trains and/or individuals thatit would be unsafe to approach a particular block, thereby avoidingcollisions.

Track circuits and other active wayside equipment require routine andfrequent maintenance throughout the track network. For track circuits inparticular, electrical insulation is required between track blocks toallow for the circuits to detect a train from one block to another. Thisimplementation requires cuts in the rail which tend to cause poor ridequality and require frequent maintenance and high installation costs.Moreover, active wayside equipment requires a power supply and frequentmaintenance.

Axle counters are also traditionally used to detect the presence of atrain in a particular track segment. For example, by counting the numberof axles that pass a particular axle counter and the number of axlesthat pass another axle counter farther down the track, it can bedetermined that a train is present in the track segment between thecounters if the number of axles counted on the latter portion of thetrack is less than the number of axles counted initially when the trainwas moving into that particular track segment.

SUMMARY OF THE INVENTION

Generally, provided are an improved system, method, and apparatus fordetermining a position of a train.

According to one preferred and non-limiting embodiment or aspect,provided is a system for determining a location of a train as it travelson a track network, comprising: an end-of-train device located on an endof the train, the end-of-train device comprising at least one signalreceiving device configured to activate and receive transponder datafrom a plurality of passive transponders located throughout at least aportion of the track network; and at least one processor incommunication with the at least one signal receiving device, the atleast one processor programmed or configured to determine a location ofthe train based at least partially on at least a portion of thetransponder data.

In one preferred and non-limiting embodiment or aspect, the at least oneprocessor is an on-board computer in a locomotive of the train and/or aprocessor in the end-of-train device.

In one preferred and non-limiting embodiment or aspect, the transponderdata stored on each passive transponder of the plurality of passivetransponders comprises an identifier that uniquely identifies at leastone track segment of the track network. In another preferred andnon-limiting embodiment or aspect, the at least one processor is furtherprogrammed or configured to correlate the location of the train with atrack database based at least partially on the identifier.

In one preferred and non-limiting embodiment or aspect, the location ofthe train determined by the at least one processor comprises a locationof a front of the train and a location of a back of the train.

In one preferred and non-limiting embodiment or aspect, the location ofthe train determined by the at least one processor comprises a locationof an end of the train.

In one preferred and non-limiting embodiment or aspect, the at least oneprocessor is further programmed or configured to: determine that aposition of the train is past a track segment corresponding to at leastone passive transponder; and transmit, to a back office system, anindication that the position of the train is past the track segment.

In one preferred and non-limiting embodiment or aspect, the systemfurther comprises a GPS receiver in communication with the at least oneprocessor, wherein the at least one processor is further programmed orconfigured to: determine a location of the train based on GPS datareceived from the GPS receiver; and determine when a passive transponderof the plurality of passive transponders is expected to be encounteredbased at least partially on the location of the train determined basedon the GPS data.

In one preferred and non-limiting embodiment or aspect, the tracknetwork comprises a plurality of switches, each switch corresponding toa clearance point on a track segment, and wherein at least one passivetransponder of the plurality of passive transponders is locatedproximate to the clearance point of each switch. In another preferredand non-limiting embodiment or aspect, at least one other passivetransponder of the plurality of passive transponders is located adjacenta track segment approaching the clearance point of each switch. Inanother preferred and non-limiting embodiment or aspect, the at leastone processor is further programmed or configured to: determine adistance traveled by the train based at least partially on measurementsreceived from a wheel tachometer; and determine if the train has passeda clearance point based at least partially on the distance traveled andthe transponder data.

According to one preferred and non-limiting embodiment or aspect,provided is a method for determining a location of a train in a tracknetwork, wherein a plurality of transponders are located throughout thetrack network, each transponder of the plurality of transponderscomprising transponder data, comprising: activating at least onetransponder with a signal receiving device located in an end-of-traindevice attached to the train as the train is traveling on a tracksegment; receiving transponder data from the at least one transponder;and determining a location of the train based at least partially on thetransponder data received from the at least one transponder.

In one preferred and non-limiting embodiment or aspect, the signalreceiving device is disposed on or in the end-of-train device.

In one preferred and non-limiting embodiment or aspect, the transponderdata stored on each transponder of the plurality of passive transponderscomprises an identifier that uniquely identifies at least one tracksegment of the track network. In another preferred and non-limitingembodiment or aspect, the method further comprises correlating thelocation of the train with a track database based at least partially onthe identifier.

In one preferred and non-limiting embodiment or aspect, the location ofthe train comprises a location of a front of the train and a location ofan end of the train.

In one preferred and non-limiting embodiment or aspect, the methodfurther comprises: determining that a position of the train is past atrack segment corresponding to at least one passive transponder; andtransmitting, to a back office system, an indication that the positionof the train is past the track segment.

In one preferred and non-limiting embodiment or aspect, the methodfurther comprises: determining a location of the train based on GPS datareceived from a GPS receiver; and determining when a transponder of theplurality of transponders is expected to be encountered based at leastpartially on the location of the train determined based on the GPS data.

In one preferred and non-limiting embodiment or aspect, the tracknetwork comprises a plurality of switches, each switch corresponding toa clearance point on a track segment, and wherein at least onetransponder of the plurality of transponders is located proximate to theclearance point of each switch. In another preferred and non-limitingembodiment or aspect, at least one other transponder of the plurality oftransponders is located adjacent a track segment approaching theclearance point of each switch.

In one preferred and non-limiting embodiment or aspect, the at least oneprocessor is further programmed or configured to: determine a distancetraveled by the train based at least partially on measurements receivedfrom a wheel tachometer; and determine if the train has passed aclearance point based at least partially on the distance traveled andthe transponder data.

According to one preferred and non-limiting embodiment or aspect,provided is an end-of-train device adapted to be attached to an end of atrain, comprising: a housing; at least one processor disposed in thehousing; and at least one signal receiving device disposed in orattached to the housing, the at least one signal receiving deviceconfigured to activate and receive transponder data from a plurality ofpassive transponders located throughout a track network, such that theat least one processor and/or an on-board computer is enabled todetermine a location of the train based at least partially on thetransponder data.

According to one preferred and non-limiting embodiment or aspect,provided is a system for determining a location of a train as it travelsin a track network, comprising: a plurality of passive transponderslocated throughout the track network, each passive transpondercomprising transponder data uniquely identifying a track segment; atleast one signal receiving device disposed in or attached to anend-of-train device, the at least one signal receiving device configuredto activate and receive transponder data from the plurality of passivetransponders; and at least one processor in communication with the atleast one signal receiving device, the at least one processor programmedor configured to: (i) determine that the train has passed a locationbased on the transponder data, and (ii) in response to determining thatthe train has passed the location, communicating an indication to a backoffice system.

Further preferred and non-limiting embodiments or aspects are set forthin the following numbered clauses.

Clause 1: A system for determining a location of a train as it travelson a track network, comprising: an end-of-train device located on an endof the train, the end-of-train device comprising at least one signalreceiving device configured to activate and receive transponder datafrom a plurality of passive transponders located throughout at least aportion of the track network; and at least one processor incommunication with the at least one signal receiving device, the atleast one processor programmed or configured to determine a location ofthe train based at least partially on at least a portion of thetransponder data.

Clause 2: The system of clause 1, wherein the at least one processor isan on-board computer in a locomotive of the train and/or a processor inthe end-of-train device.

Clause 3: The system of clause 1 or 2, wherein the transponder datastored on each passive transponder of the plurality of passivetransponders comprises an identifier that uniquely identifies at leastone track segment of the track network.

Clause 4: The system of any of clauses 1-3, wherein the at least oneprocessor is further programmed or configured to correlate the locationof the train with a track database based at least partially on theidentifier.

Clause 5: The system of any of clauses 1-4, wherein the location of thetrain determined by the at least one processor comprises a location of afront of the train and a location of a back of the train.

Clause 6: The system of any of clauses 1-5, wherein the location of thetrain determined by the at least one processor comprises a location ofan end of the train.

Clause 7: The system of any of clauses 1-6, wherein the at least oneprocessor is further programmed or configured to: determine that aposition of the train is past a track segment corresponding to at leastone passive transponder; and transmit, to a back office system, anindication that the position of the train is past the track segment.

Clause 8: The system of any of clauses 1-7, further comprising a GPSreceiver in communication with the at least one processor, wherein theat least one processor is further programmed or configured to: determinea location of the train based on GPS data received from the GPSreceiver; and determine when a passive transponder of the plurality ofpassive transponders is expected to be encountered based at leastpartially on the location of the train determined based on the GPS data.

Clause 9: The system of any of clauses 1-8, wherein the track networkcomprises a plurality of switches, each switch corresponding to aclearance point on a track segment, and wherein at least one passivetransponder of the plurality of passive transponders is locatedproximate to the clearance point of each switch.

Clause 10: The system of any of clauses 1-9, wherein at least one otherpassive transponder of the plurality of passive transponders is locatedadjacent a track segment approaching the clearance point of each switch.

Clause 11: The system of any of clauses 1-10, wherein the at least oneprocessor is further programmed or configured to: determine a distancetraveled by the train based at least partially on measurements receivedfrom a wheel tachometer; and determine if the train has passed aclearance point based at least partially on the distance traveled andthe transponder data.

Clause 12: A method for determining a location of a train in a tracknetwork, wherein a plurality of transponders are located throughout thetrack network, each transponder of the plurality of transponderscomprising transponder data, comprising: activating at least onetransponder with a signal receiving device located in an end-of-traindevice attached to the train as the train is traveling on a tracksegment; receiving transponder data from the at least one transponder;and determining a location of the train based at least partially on thetransponder data received from the at least one transponder.

Clause 13: The method of clause 12, wherein the signal receiving deviceis disposed on or in the end-of-train device.

Clause 14: The method of clause 12 or 13, wherein the transponder datastored on each transponder of the plurality of passive transponderscomprises an identifier that uniquely identifies at least one tracksegment of the track network.

Clause 15: The method of any of clauses 12-14, further comprisingcorrelating the location of the train with a track database based atleast partially on the identifier.

Clause 16: The method of any of clauses 12-15, wherein the location ofthe train comprises a location of a front of the train and a location ofan end of the train.

Clause 17: The method of any of clauses 12-16, further comprising:determining that a position of the train is past a track segmentcorresponding to at least one passive transponder; and transmitting, toa back office system, an indication that the position of the train ispast the track segment.

Clause 18: The method of any of clauses 12-17, further comprising:determining a location of the train based on GPS data received from aGPS receiver; and determining when a transponder of the plurality oftransponders is expected to be encountered based at least partially onthe location of the train determined based on the GPS data.

Clause 19: The method of any of clauses 12-18, wherein the track networkcomprises a plurality of switches, each switch corresponding to aclearance point on a track segment, and wherein at least one transponderof the plurality of transponders is located proximate to the clearancepoint of each switch.

Clause 20: The method of any of clauses 12-19, wherein at least oneother transponder of the plurality of transponders is located adjacent atrack segment approaching the clearance point of each switch.

Clause 21: The method of any of clauses 12-20, wherein the at least oneprocessor is further programmed or configured to: determine a distancetraveled by the train based at least partially on measurements receivedfrom a wheel tachometer; and determine if the train has passed aclearance point based at least partially on the distance traveled andthe transponder data.

Clause 22: An end-of-train device adapted to be attached to an end of atrain, comprising: a housing; at least one processor disposed in thehousing; and at least one signal receiving device disposed in orattached to the housing, the at least one signal receiving deviceconfigured to activate and receive transponder data from a plurality ofpassive transponders located throughout a track network, such that theat least one processor and/or an on-board computer is enabled todetermine a location of the train based at least partially on thetransponder data.

Clause 23: A system for determining a location of a train as it travelsin a track network, comprising: a plurality of passive transponderslocated throughout the track network, each passive transpondercomprising transponder data uniquely identifying a track segment; atleast one signal receiving device disposed in or attached to anend-of-train device, the at least one signal receiving device configuredto activate and receive transponder data from the plurality of passivetransponders; and at least one processor in communication with the atleast one signal receiving device, the at least one processor programmedor configured to: (i) determine that the train has passed a locationbased on the transponder data, and (ii) in response to determining thatthe train has passed the location, communicating an indication to a backoffice system.

These and other features and characteristics of the present invention,as well as the methods of operation and functions of the relatedelements of structures and the combination of parts and economies ofmanufacture, will become more apparent upon consideration of thefollowing description and the appended claims with reference to theaccompanying drawings, all of which form a part of this specification,wherein like reference numerals designate corresponding parts in thevarious figures. It is to be expressly understood, however, that thedrawings are for the purpose of illustration and description only andare not intended as a definition of the limits of the invention. As usedin the specification and the claims, the singular form of “a”, “an”, and“the” include plural referents unless the context clearly dictatesotherwise.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic diagram of one embodiment of a system fordetermining a position of an end-of-train device according to theprinciples of the present invention;

FIG. 2 illustrates a step diagram for a method of determining a positionof an end-of-train device according to the principles of the presentinvention;

FIG. 3 illustrates a train traveling in a track network according to theprinciples of the present invention; and

FIG. 4 illustrates a step diagram for a method of determining a positionof an end-of-train device according to the principles of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

For purposes of the description hereinafter, the terms “upper”, “lower”,“right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, “lateral”,“longitudinal,” and derivatives thereof shall relate to the invention asit is oriented in the drawing figures. However, it is to be understoodthat the invention may assume various alternative variations and stepsequences, except where expressly specified to the contrary. It is alsoto be understood that the specific devices and processes illustrated inthe attached drawings, and described in the following specification, aresimply exemplary embodiments of the invention. Hence, specificdimensions and other physical characteristics related to the embodimentsdisclosed herein are not to be considered as limiting.

As used herein, the terms “communication” and “communicate” refer to thereceipt, transmission, or transfer of one or more signals, messages,commands, or other type of data. For one unit or device to be incommunication with another unit or device means that the one unit ordevice is able to receive data from and/or transmit data to the otherunit or device. A communication may use a direct or indirect connection,and may be wired and/or wireless in nature. Additionally, two units ordevices may be in communication with each other even though the datatransmitted may be modified, processed, routed, etc., between the firstand second unit or device. It will be appreciated that numerousarrangements are possible. Any known electronic communication protocolsand/or algorithms may be used such as, for example, TCP/IP (includingHTTP and other protocols), WLAN (including 802.11 and other radiofrequency-based protocols and methods), analog transmissions, cellularnetworks (e.g., Global System for Mobile Communications (GSM), CodeDivision Multiple Access (CDMA), Long-Term Evolution (LTE), WorldwideInteroperability for Microwave Access (WiMAX), etc.), and/or the like.

In a preferred and non-limiting embodiment of the present invention,provided is a system, method, and apparatus for determining a locationof a train, and particularly, a location of an end of a train. Thesystem includes a plurality of passive transponders located throughout atrack network that each include transponder data uniquely identifying atrack segment or location where the transponder is positioned, such as,but not limited to, a portion of a track, a switch, a region,coordinates, and/or the like. The transponder data may be any type ofdata that uniquely identifies a track segment or location and, in apreferred and non-limiting embodiment, includes a unique identifier thatcan be correlated with a track location from a track database. Moreover,the transponders may be located anywhere throughout a track network and,in a preferred and non-limiting embodiment, may be located adjacent aclearance point of a switch or adjacent a track segment approaching aclearance point of a switch. However, it will be appreciated thattransponders may be positioned at other locations throughout the tracknetwork to control movement of multiple trains by establishingboundaries that may be used to hold trains in a particular location fortraffic control or the like.

A train includes an end-of-train (EOT) device arranged on an end of thetrain (e.g., on an end of a rear railcar) that includes a signalreceiving device. The passive transponders and signal receiving deviceare configured such that when a train is traveling on a track, thesignal receiving device activates and receives data from the stationarytransponders. Thus, the transponders may be located on the track,adjacent the track, or in sufficient proximity to the track such thatthe signal receiving device is able to communicate with them. Using thetransponder data stored on the transponders, an on-board computer on thetrain and/or the EOT device determines a location of the train and,particularly, a location of an end of the train relative to the track.By using passive transponders rather than active wayside equipment, lessmaintenance is required.

Referring to FIG. 1, a system 1000 for determining a location of a train116 is shown according to a preferred and non-limiting embodiment oraspect. The train 116 is traveling on a track 112 and includes alocomotive 114 and an EOT device 101. An on-board computer 109 locatedin the locomotive 114 is in communication with a track database 106 inthe locomotive 114 or elsewhere on the train 116, and a remote backoffice system 104. The EOT device 101 includes a signal receiving device110 which communicates with a transponder 102 when in sufficientproximity to the transponder 102. In preferred and non-limitingembodiments or aspects, an additional signal receiving device 113 may belocated in the locomotive 114 or another railcar and may be configuredto communicate with the transponder 102.

With continued reference to the preferred and non-limiting embodiment oraspect shown in FIG. 1, the transponder 102 may include any signalemitting device that communicates data in response to being activated.For example, the transponder 102 may be a passive radio frequencyidentification (RFID) transponder (e.g., tag) and the signal receivingdevice 110 may be an RFID reader that energizes the transponder 102 toretrieve data stored thereon. It will be appreciated, however, that thetransponder 102 may include any number of signal-emitting devices suchas, for example, near field communication (NFC) tags, low-powerBluetooth® devices, and/or the like, and that the signal receivingdevice 110 may include any device capable of communicating with thetransponder 102. The plurality of transponders 102 located throughoutthe track network may be the same type of transponder or, in otherexamples, may differ such that more than one type of signal receivingdevice 110 is used in the EOT device, or the signal receiving device 110may be programmed or configured to communicate with different types oftransponders 102 using different communication protocols. It will beappreciated that other variations are possible.

In some non-limiting examples, a plurality of printed data sources(e.g., a two- or three-dimensional barcode, a visual code, printed text,etc.) may be used. In such examples, the EOT device is configured toilluminate the printed data source (e.g., with an infrared light oranother light source) and capture the data printed thereon with an imagecapture device. The EOT device and/or on-board computer may then decodeand/or process the captured image to obtain the data encoded or printedthereon.

Still referring to FIG. 1, the on-board computer 109 may be incommunication with a positioning system, such as a Global PositioningSystem (GPS) satellite 103 (wherein the on-board computer 109 is incommunication with a GPS receiver 120 on the train 116), to determine orreceive positional coordinates of the train 116. Various othertechniques may also be used to determine the position of the train 116such as, for example, axle counters, signal triangulation, wheeltachometers, and/or the like. The on-board computer 109 may use datareceived from the transponders 102 to confirm and/or verify the locationof the train as determined by GPS and/or other methods. In this manner,the transponders 102 may be used as a failsafe mechanism for verifyingthat the location of the train 116, as determined by the GPS, axlecounters, signal triangulation, wheel tachometers, and/or the like, iscorrect.

The location of the train 116, as determined by GPS and/or othermethods, may also be used to determine when a transponder 102 isexpected to be encountered. This provides information for the EOT device101 to anticipate a transponder 102 so that it can activate thetransponder 102 at the appropriate time. Because activating atransponder 102 utilizes power, attempting to activate a transponder 102only when it is anticipated, rather than continually or periodically,minimizes the amount of power that the EOT device 101 consumes. It willbe appreciated, however, that the transponders 102 may also be used as aprimary source for determining train location, and that GPS and/or otherlike devices and methods may be used to confirm such determinations ormay not be used at all. In preferred and non-limiting embodiments oraspects, and as discussed above, a GPS receiver 120 may be located inthe locomotive 114 and/or the EOT device 101. In preferred andnon-limiting embodiments or aspects, in which a GPS receiver 120 islocated in both the locomotive 114 and the EOT device 101, the locationdata received from both GPS receivers 120 may be used to determine orconfirm the length of the train 116. Methods for determining the overalllength of a train are described in U.S. Pat. No. 6,081,769 to Curtis,the disclosure of which is hereby incorporated by reference in itsentirety.

In the preferred and non-limiting embodiment or aspect shown in FIG. 1,the back office system 104 includes a back office system server 105 anda remote track database 107. The on-board computer 109 generates reportdata 108 and communicates this data to the back office system server105, which stores the report data 108 or a portion thereof in the remotetrack database 107. The report data 108 may include the transponder dataand/or be generated by the on-board computer 109 based on various inputsincluding, for example, the transponder data obtained from the signalreceiving device 110. It will be appreciated that the report data 108may also include raw, unprocessed data received from the signalreceiving device 110 (e.g., the transponder data itself), or may beprocessed and/or combined with other data by the EOT device 101 and/oron-board computer 109. Moreover, in preferred and non-limitingembodiments or aspects, the EOT device 101 may also be in communicationwith the back office system 104 and may transmit report data 108received from the transponder 102 and/or derived from the transponderdata directly to the back office system server 105 upon receiving it orat intervals.

With continued reference to FIG. 1, the report data 108 may becommunicated to the back office system server 105 as it is receivedand/or determined, or may be communicated at a predetermined interval ortime period. For example, once a position of the EOT device 101 isconfirmed to have passed a transponder 102 (or some other location onthe track 112), the on-board computer 109 and/or EOT device 101 maytransmit the report data 108 to the back office system server 105 whereit is stored in the remote track database 107. The report data 108 canthen be used by the back office system server 105, other remote systems,and/or railroad personnel to make decisions for safely moving switchesor routing trains through the track network. It will be appreciated thatthe back office system server 105 and/or other remote systems mayimplement one or more algorithms for generating train and/or switchcommands based on the report data 108.

In a preferred and non-limiting embodiment or aspect, the transponderdata stored on each of the transponders 102 includes a unique identifierthat uniquely identifies the transponder 102 and/or a location of thetransponder 102. For example, a unique identifier from a transponder maycorrespond to a track location in the track database(s) 106, 107, suchthat the position of the train 116, and particularly the position of thefront and/or end of the train 116, can be correlated with the trackdatabase(s) 106, 107. In a non-limiting example, the track database(s)106, 107 include identifiers corresponding with track locations (e.g.,geographic locations, landmark-based locations, specific track segmentsor switches, etc.), such that the unique identifier from the transponderdata may be matched to an identifier in the track database(s) 106, 107to determine a track location. Unique identifiers may be in any suitableformat such as, for example, integers, alphanumeric strings,coordinates, and/or the like. In this manner, the on-board computer 109may receive the transponder data from a transponder 102, extract ordetermine a unique identifier from the transponder data, and look-up theunique identifier on the on-board track database 106 to find acorresponding identifier associated with a track location. The on-boardcomputer 109 may then generate the report data 108 based on the uniqueidentifier and/or corresponding information retrieved from the trackdatabase. It will be appreciated that transponder data may alternativelyor additionally be correlated with the remote track database 107.

In a preferred and non-limiting embodiment or aspect, a failsafeprotocol may be implemented by the on-board computer 109 and/or EOTdevice 101 to confirm the detection of a transponder 102. In suchembodiments or aspects, a signal receiving device 113 in the locomotive114 and a signal receiving device 110 in the EOT device 101 may bothdetect and/or obtain transponder data from the transponders 102. Theon-board computer 109 and/or EOT device 101 may then compare thetransponder data and/or ensure that transponder data is received by bothsignal receiving devices 110, 113.

Referring to FIG. 3, a train 116 traveling in a track network is shownaccording to a preferred and non-limiting embodiment or aspect. Aclearance transponder 304 may be located at a clearance point of aswitch 306 in the track network to facilitate a determination of whenthe train 116 has passed the clearance point. A switch 306 may have twoclearance points, one for each leg of the switch 306, and therefore twoclearance transponders. Depending on which leg of the switch the trainwas traveling, one of the two clearance transponders may be activated.Once it is determined that the train 116 has passed the clearancetransponder 304, and therefore the clearance point, the switch 306 canbe moved or another train can be routed on the associated track segment.An approach transponder 302 is located at a distance (d) from the switch306 on the track, and the clearance transponder 304 is locatedsubstantially proximate to the switch 306. It will be appreciated thatthe clearance transponder 304 may also be located at a distance past theswitch 306 or elsewhere. The EOT device 101 at the end of the train 116has a signal-receiving device (not shown) for receiving data from thetransponders 302, 304.

With continued reference to FIG. 3, after passing over the approachtransponder 302, the signal-receiving device obtains transponder datafrom the transponder 302. The transponder data received from theapproach transponder 302 may be used to confirm that the signalreceiving device is working properly as the train 116 approaches aclearance transponder 304 located at a clearance point of the switch306, and to indicate to the EOT device 101 and/or on-board computer ofthe train 116 that detection of another transponder (e.g., the clearancetransponder 304) can be expected. For example, approach transponder 302may be located at a distance (d) from the switch 306 or anotherclearance point to account for GPS position errors. After detecting theapproach transponder 302, the on-board computer and/or EOT device 101 ofthe train 116 may then utilize any suitable method or device fordetermining the distance traveled, such as but not limited to a wheeltachometer, to independently determine when the clearance pointassociated with the clearance transponder 304 can be expected. In somepreferred and non-limiting embodiments or aspects, two or moretransponders may be used in any given location or region for redundancy.Transponders may also be used in connection with other clearance points,such as train stations, authority blocks, and/or the like.

Referring now to FIG. 2, a method for determining the location of an EOTdevice is shown according to a preferred and non-limiting embodiment oraspect. At a first step 200, the position of the EOT device isdetermined using GPS or another suitable method. At a next step 202, theEOT device detects a stationary transponder in the track network. Atstep 204, the EOT device receives transponder data from the transponderby, for example, activating a passive transponder. Next, at step 205,the on-board computer, EOT device, and/or another computing devicecorrelates a unique identifier from the transponder data to a tracklocation in a track database. At step 206, the on-board computer, EOTdevice, and/or another computing device may confirm that the position ofthe EOT device is past a clearance point based on the transponder datareceived from the transponder and the corresponding track locationretrieved from the track database. At step 208, the transponder data maybe submitted to a back office system.

In a preferred and non-limiting embodiment, the on-board computerdetermines that the position of the train and/or EOT device is past aparticular track segment. The on-board computer may also use the EOTdevice position to release authority for a following train to use thetrack segment. Thus, the data submitted to a back office system mayinclude a location of the front of the train, a location of the end ofthe train (or EOT device), and/or a release of movement authority.

Referring now to FIG. 4, a method for determining the location of an EOTdevice using an approach transponder is shown according to a preferredand non-limiting embodiment or aspect. At a first step 400, a firsttransponder (e.g., an approach transponder) is detected by a signalreceiving device. Then, at step 402, transponder data is received fromthe first transponder. Using this transponder data, the operability ofthe signal receiving device can be confirmed. At step 404, the distancetraveled by the train is measured using, for example, any suitablemethod or device for determining the distance traveled, such as, but notlimited to, a wheel tachometer. Then, at step 406, a second transponderis detected at a clearance point. Transponder data is then received fromthe second transponder at a next step 408. At step 410, at least aportion of the transponder data, such as but not limited to anindication that the train has passed the clearance point, is transmittedto a back office system.

In a preferred and non-limiting embodiment or aspect, the system 1000for determining a location of a train 116 can be used for implementingmoving block train control without the need for active waysideequipment. By determining the locations of trains throughout a tracknetwork with the system 1000, one or more movement authorities mayfacilitate movement of the trains at a closer proximity.

In non-limiting embodiments or aspects, a method to determine thelocation of a train may be performed by at least one non-transitorycomputer-readable medium including program instructions that, whenexecuted by at least one processor, cause one or more devices to performthe steps. With the sole exception of transitory propagating signals, anon-transitory computer-readable medium may include any medium capableof storing data such as, but not limited to, random-access memory (RAM),read-only memory (ROM), hard drives, compact and floppy discs, and/orother like mediums.

Although the invention has been described in detail for the purpose ofillustration based on what is currently considered to be the mostpractical and preferred embodiments or aspects, it is to be understoodthat such detail is solely for that purpose and that the invention isnot limited to the disclosed embodiments or aspects, but, on thecontrary, is intended to cover modifications and equivalent arrangementsthat are within the spirit and scope of the appended claims. Forexample, it is to be understood that the present invention contemplatesthat, to the extent possible, one or more features of any embodiment canbe combined with one or more features of any other embodiment or aspect.

What is claimed is:
 1. A system for determining a location of a train asit travels on a track network, comprising: an end-of-train devicelocated on an end of the train, the end-of-train device comprising atleast one signal receiving device configured to activate and receivetransponder data from a plurality of passive transponders locatedthroughout at least a portion of the track network; and at least oneprocessor in communication with the at least one signal receivingdevice, the at least one processor programmed or configured to determinea location of the train based at least partially on at least a portionof the transponder data.
 2. The system of claim 1, wherein the at leastone processor is an on-board computer in a locomotive of the trainand/or a processor in the end-of-train device.
 3. The system of claim 1,wherein the transponder data stored on each passive transponder of theplurality of passive transponders comprises an identifier that uniquelyidentifies at least one track segment of the track network.
 4. Thesystem of claim 3, wherein the at least one processor is furtherprogrammed or configured to correlate the location of the train with atrack database based at least partially on the identifier.
 5. The systemof claim 1, wherein the location of the train determined by the at leastone processor comprises a location of a front of the train and alocation of a back of the train.
 6. The system of claim 1, wherein thelocation of the train determined by the at least one processor comprisesa location of an end of the train.
 7. The system of claim 1, wherein theat least one processor is further programmed or configured to: determinethat a position of the train is past a track segment corresponding to atleast one passive transponder; and transmit, to a back office system, anindication that the position of the train is past the track segment. 8.The system of claim 1, further comprising a GPS receiver incommunication with the at least one processor, wherein the at least oneprocessor is further programmed or configured to: determine a locationof the train based on GPS data received from the GPS receiver; anddetermine when a passive transponder of the plurality of passivetransponders is expected to be encountered based at least partially onthe location of the train determined based on the GPS data.
 9. Thesystem of claim 1, wherein the track network comprises a plurality ofswitches, each switch corresponding to a clearance point on a tracksegment, and wherein at least one passive transponder of the pluralityof passive transponders is located proximate to the clearance point ofeach switch.
 10. The system of claim 9, wherein at least one otherpassive transponder of the plurality of passive transponders is locatedadjacent a track segment approaching the clearance point of each switch.11. The system of claim 10, wherein the at least one processor isfurther programmed or configured to: determine a distance traveled bythe train based at least partially on measurements received from a wheeltachometer; and determine if the train has passed a clearance pointbased at least partially on the distance traveled and the transponderdata.
 12. A method for determining a location of a train in a tracknetwork, wherein a plurality of transponders are located throughout thetrack network, each transponder of the plurality of transponderscomprising transponder data, comprising: activating at least onetransponder with a signal receiving device located in an end-of-traindevice attached to the train as the train is traveling on a tracksegment; receiving transponder data from the at least one transponder;and determining a location of the train based at least partially on thetransponder data received from the at least one transponder.
 13. Themethod of claim 12, wherein the signal receiving device is disposed onor in the end-of-train device.
 14. The method of claim 12, wherein thetransponder data stored on each transponder of the plurality of passivetransponders comprises an identifier that uniquely identifies at leastone track segment of the track network.
 15. The method of claim 14,further comprising correlating the location of the train with a trackdatabase based at least partially on the identifier.
 16. The method ofclaim 12, wherein the location of the train comprises a location of afront of the train and a location of an end of the train.
 17. The methodof claim 12, further comprising: determining that a position of thetrain is past a track segment corresponding to at least one passivetransponder; and transmitting, to a back office system, an indicationthat the position of the train is past the track segment.
 18. The methodof claim 12, further comprising: determining a location of the trainbased on GPS data received from a GPS receiver; and determining when atransponder of the plurality of transponders is expected to beencountered based at least partially on the location of the traindetermined based on the GPS data.
 19. The method of claim 12, whereinthe track network comprises a plurality of switches, each switchcorresponding to a clearance point on a track segment, and wherein atleast one transponder of the plurality of transponders is locatedproximate to the clearance point of each switch.
 20. The method of claim19, wherein at least one other transponder of the plurality oftransponders is located adjacent a track segment approaching theclearance point of each switch.
 21. The method of claim 12, wherein theat least one processor is further programmed or configured to: determinea distance traveled by the train based at least partially onmeasurements received from a wheel tachometer; and determine if thetrain has passed a clearance point based at least partially on thedistance traveled and the transponder data.
 22. An end-of-train deviceadapted to be attached to an end of a train, comprising: a housing; atleast one processor disposed in the housing; and at least one signalreceiving device disposed in or attached to the housing, the at leastone signal receiving device configured to activate and receivetransponder data from a plurality of passive transponders locatedthroughout a track network, such that the at least one processor and/oran on-board computer is enabled to determine a location of the trainbased at least partially on the transponder data.
 23. A system fordetermining a location of a train as it travels in a track network,comprising: a plurality of passive transponders located throughout thetrack network, each passive transponder comprising transponder datauniquely identifying a track segment; at least one signal receivingdevice disposed in or attached to an end-of-train device, the at leastone signal receiving device configured to activate and receivetransponder data from the plurality of passive transponders; and atleast one processor in communication with the at least one signalreceiving device, the at least one processor programmed or configuredto: (i) determine that the train has passed a location based on thetrack data, and (ii) in response to determining that the train haspassed the location, communicating an indication to a back officesystem.